Reporter: It's one of the decade's most successful pop hits. But now, this platinum-selling anthem about a bitter breakup is the focus of an even more bitter battle, between singer kelly clarkson, and the man behind it, music mogul clive davis. Clarkson came out swinging online late tuesday. Accusing her former producer of spreading misinformation. In his n memoir, "the soundtrack of my life." In the book, davis says clarkson, who won "american idol," didn't want to include the now-hit song, "since you've been gone," on her 2004 album. He says, when he insisted, she, quote, burst into historical sobbing. But the grammy award winner is firing back. Clarkson said the only time she cried was when she played davis the song "because of you," which she co-wrote. Davis said she was a, quote, expletive writer, who should be grateful for the gifts that he bestows upon me. It's clear that kelly clarkson has a vivid memory and strong recollection. And she wanted to make that known. Reporter: This morning's war of words comes just as davis is releasing his memoir. This week, he sat down with lara to talk about his long career. I believe in the future of music. I take it seriously. I believe in hard work. Reporter: This morning, isn't discounting clarkson's hard work, just her version of what happened. Saying, I am truly very sorry that she has decided to take issue with what I know to be an accurate depiction of our time together. For "good morning america," abbie boudreau, abc news, los angeles.

This transcript has been automatically generated and may not be 100% accurate.

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